


human duet

by starboykeith



Category: Voltron: Legendary Defender
Genre: Barebacking, Bottom Keith (Voltron), Creampie, Established Relationship, First Time, Loss of Virginity, M/M, Plot What Plot/Porn Without Plot, Riding, Season 2, Sexual Content, Size Difference, Size Kink
Language: English
Status: Completed
Published: 2018-10-05
Updated: 2018-10-05
Packaged: 2019-07-13 12:45:07
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,931
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16018187
Author URL: https://archiveofourown.org/users/starboykeith/pseuds/starboykeith
Summary: They trust each other with their lives, but Shiro didn't trust himself with this. Until now.





	human duet

**Author's Note:**

> i wrote most of this after season 2 so that’s how i imagined them for this fic. obviously it’s slightly not canon compliant as we didn’t know then about adam
> 
> title from animal impulses by iamx

Shiro’s big.

Keith knows and loves this. He loves the thickness of Shiro’s cock in his hand, the weight of it on his tongue. Shiro’s always real careful opening Keith up with his fingers; he takes his time, gets Keith all messy with lube, stretches him so slow and careful and _thorough_ that just the prep pushes Keith to the limit. He arches his back and thrusts down on Shiro’s fingers and tries to muffle his moans in the pillow because he knows Shiro's attention to detail, and if Keith gets too mouthy Shiro will take even _longer_. Shiro’s the one who decides when Keith comes.

More often than not, Keith comes just from having Shiro’s fingers in him, tears running down his cheeks and voice cracking as he begs, so full and open he can barely stand it and still desperate for more, getting hard again at the thought of being stretched wide on Shiro’s cock. It makes Keith’s mouth water to even think of how Shiro would feel, how Shiro would split him open and make him ache for days.

However, it’s only a thought.

No matter how many times Keith asks or pleads or begs, Shiro refuses to fuck him. It’s usually Keith who initiates their sexual encounters. They only go as far as Shiro wants, and his limit is stretching Keith on two fingers, no matter how many times Keith insists he’s fingered himself up to three.

They trust each other with their lives, but Shiro doesn’t trust himself with this.

Shiro outright refused the prospect of them having sex, and Keith’s fine with that, he really is – he gets that Shiro isn't comfortable, so afraid of hurting Keith he won’t even consider it. It's always been a _very_ attractive prospect to Keith, but all Shiro saw and fretted and worried about was the pain.

Keith doesn’t pressure him, would never force Shiro into anything he didn’t want, but he can’t help wishing Shiro would just _fuck_ him.

He curls a hand around the back of Shiro's neck, bringing him closer, and their kiss turns slow and lazy, long presses of tongues and lips and Shiro makes a low, satisfied noise and pulls back to kiss Keith's neck instead.

Keith hums and tightens his leg around Shiro's waist. He's been hard for a while, can feel Shiro is too, but it's nice like this, holding each other close.

“Keith?” Shiro whispers, and he's still hiding his face but the kissing has stopped, and Keith arches until Shiro presses an acquiescent kiss against his jaw.

“Yeah?”

“I wanted to ask you something.”

“Then ask,” Keith says, amused, but he's concerned when Shiro doesn't respond. “Shiro?”

Shiro doesn't move, and so Keith can't see his expression when he says, “Um – if you wanted to, maybe, I was wondering.” He sounds more unsure with each word. “If you wanted to go all the way,” he finally manages, and Keith's eyebrows raise.

“Like,” he says slowly, “ _all_ the way?”

Shiro finally looks at him, and he's biting his lip and tilting his head in an adorable way that would usually make Keith weak, but he's too surprised to do anything but stare.

“I mean,” Shiro says quickly, “it's okay if you don't want to, we don't have to – “

“No,” Keith blurts out, desperate to fix his mistake. “Are you kidding, of course I – “ He cuts himself off to kiss Shiro quick and hard on the mouth. “ _Yes_ ,” he says emphatically.

“We can take it slow,” Shiro says, but there's a smile curling his lips.

Keith smirks. “Maybe not,” he says, and Shiro goes pink.

In all honesty, Keith’s been waiting for this for months.

“Are you sure?" he asks. "I know you were – nervous.”

Nervous is an understatement.

“I want you,” Shiro says, and his voice has gone all rough and Keith moans helplessly when he rolls his hips down. “I want to make you feel good.”

“You already do,” Keith tells him seriously.

Shiro gets up to go to his bedside drawer, stripping his shirt off as he goes, and Keith watches the shift of his shoulders, biting his lip. Keith's already down to boxers and he stands up to take them off, then positions himself in the middle of the bed, head in the pillows and watching Shiro with dark eyes.

He still blushes at Shiro's heated gaze and the bed dips as Shiro crawls over him, tossing the lube beside them and kissing Keith hard. When he withdraws, it’s just to push a pillow under Keith’s hips and Keith shifts until he’s comfortable.

The click of the lube opening is loud in the quiet room and Shiro swallows as he drizzles it over his fingers, too much as usual. The first finger he presses to Keith’s hole is gentle, testing the pressure as he rubs in a circle, his other hand coming to Keith’s thigh to keep him spread open.

They know this, they’re good at this, but it feels different. Keith feels restless, as though their first time will be different somehow to the countless times Shiro’s opened him up before.

When Keith’s relaxed enough to take Shiro’s first finger, moving in gentle circles inside him, Shiro slides in the second and Keith tenses, biting back a moan and nodding when Shiro raises cautious eyes to his own.

Pleasure builds slow and then fast, heat collecting behind Keith’s navel and he arches his back, groaning when Shiro’s fingers slide deeper. Shiro’s searching for his prostate, curling his fingers and Keith spreads his legs wider, needing to feel completely pulled open, to be at Shiro’s mercy. Shiro’s teasing, fingers just brushing Keith’s prostate, and Keith moans in frustration and fists a hand in Shiro’s hair, tugging his face up for a kiss.

Shiro moves faster, thrusting in and out, his other hand a tight grip on Keith’s thigh and Keith finds himself at the precipice too soon, panting for breath and bringing his knees up, curling into himself.

“Shiro, stop,” he gasps and Shiro's fingers still, eyes snapping to Keith in concern. “I can't, I'm gonna come.”

“It'll help you relax,” Shiro says, but he stays still, hesitantly asking, “Do you want me to stop?”

Keith’s wound so tight the words register a moment later, and he shakes his head – if it'll help him relax, he thinks, it's okay, and he doesn't think he could hold on any longer anyway.

“Don't stop,” Keith says, and makes a strangled noise when Shiro twists his fingers, thrusting them faster and Keith throws a hand over his face, overwhelmed.

“That's it,” Shiro says, and the encouragement coils pleasure tight in Keith's belly and then Shiro grazes his prostate and –

“ _Shiro_ ,” Keith gasps, and Shiro's _watching_ him, watching him come all over his chest and then his gaze dips between Keith's legs and Keith squirms, embarrassed.

“Fuck, Keith,” Shiro says breathlessly, and Keith remembers how Shiro likes it when he clenches down on his fingers.

He wonders if Shiro will like it even more when Keith's clenching down on his cock.

Shiro fumbles for the sheet and hastily wipes the come from Keith's stomach, and Keith wrinkles his nose.

“My hero,” he drawls, and Shiro grins.

“Shut up,” he says, and Keith can't maintain his unimpressed expression when Shiro touches his third finger to the rim. “Can you take another?”

Keith swallows. Shiro’s fingers are bigger than his, and he’s only ever taken two of them. He reminds himself his true prize will be even bigger, and it’ll be worth the slight discomfort of prep.

“Yeah,” he says weakly. Shiro looks suspicious, opening his mouth to argue, no doubt, so Keith clenches around his fingers again and pulls moans from both of them.

Shiro nods, probably more for his own benefit than Keith’s, and he starts pushing in again. Keith’s body puts up more resistance to the third finger and he breathes deeply, making a conscious effort to untense his muscles.

“Okay?” Shiro asks. He sounds worried and Keith tries harder to relax, determined not to lose the opportunity Shiro’s finally offered him. Shiro’s still pushing in steadily and it starts to feel better, even _good_ , when he curls his fingers, stroking against Keith’s prostate and providing ample distraction from the burning stretch.

“Yeah,” Keith says finally. When he exhales, his tension goes with it, and he cries out at the sudden concentration of pleasure. “It’s good,” he murmurs, watching Shiro’s pupils dilate.

“Good,” Shiro says, pleased, and it’s a shock to realise Keith’s taking all three of his fingers to the root, so full he can hardly breathe.

Shiro doesn’t withdraw, though: keeps twisting and curling his fingers inside Keith, moving them in gentle circles and ensuring Keith’s stretched and ready for him.

“I’m ready,” Keith says, breathless with impatience.

“Okay,” Shiro says, finally pulling out and leaning over Keith again to kiss him. Keith sucks Shiro’s bottom lip, hands splaying over his back as Shiro adjusts his position, moving between Keith’s legs. “Are you sure?”

“Of course I'm sure,” Keith says, and it sounds like a boast but really, he's been waiting months for this. He can handle it. He's about to lose his virginity to Shiro. No big deal.

Shiro's gaze drags hotly over him, and Keith fights the urge to close his legs, face feeling suddenly warm.

“No condoms in space,” Shiro says nervously, and Keith swallows.

“I'm clean,” he says. “I've never actually – “

“Me neither,” Shiro says, embarrassed, and Keith had never asked but he's surprised. He’d figured Shiro was reticent because of past experiences, not – _no_ experience.

“It's okay, Shiro,” Keith says, and when he reaches out Shiro comes closer, placing one hand carefully beside Keith's head for balance, other hand guiding his cock to Keith's hole and _this is it_ , Keith thinks frantically.

“ _Oh_ ,” spills from his mouth as Shiro starts pressing inside, gently, so gently but he's so big, not even the head inside and Keith's already panting, tensing so hard Shiro moans, frustrated.

“Relax, baby,” he says, full of concern, and Keith tries, he really does, but it _hurts_. Shiro's hand fists in the sheet beside his head, and he puts his other hand on Keith's chest, rubbing at a nipple and Keith can't help but moan, back arching because Shiro _knows_ he's sensitive, knows it will distract him.

“Mm,” Keith manages, and it hurts as Shiro pushes deeper, but Shiro's still playing with his nipples and Keith inhales sharply as Shiro pinches hard. “Shiro, fuck,” he says, and Shiro _smirks_ at him and Keith swears his cock twitches at the sight.

When Shiro bottoms out, they’re both panting. Keith relaxes his grip on Shiro’s shoulders, incoherent and gasping at the stretch of it, unable to do anything but _feel_ , and it’s so much more than Shiro’s fingers Keith thinks he might die, clutching at the sheets and Shiro’s back and anything to ground himself, dangerously close and unbearably full.

Shiro starts moving in small increments, and it’s easier to relax when he’s pulled out and pushing back in, the burn of it more tolerable by the second. He’s being so _careful_ , so fucking slow, biting his lip in concentration, and he's holding himself with such tension Keith is concerned.

“Hey,” Keith says, reaching up to touch Shiro's face, “are you okay? Is this okay?”

Shiro nods immediately, and Keith’s reassured. “Yeah,” Shiro mumbles, “but I don't want to hurt you.”

Keith pushes up and squeezes around him, around the thickness of Shiro stretching him open, world narrowing to the sensitive point where they're connected in the most primal way, and Shiro moans helplessly, hips stilling as he tries to control himself, which is the last thing Keith wants.

“It's okay,” Keith breathes, looking at Shiro as he slowly moves his palm to the centre of Shiro's back, tightens his legs around Shiro's waist, and then –

Keith flips them over, a move he would not have been able to pull off if Shiro wasn't uncertain and unmoving and afraid of hurting him.

It takes Keith a moment to adjust – it's so much _deeper_ , taking it like this, fuller than he'd thought possible – and the sudden movement shocks startled moans from them both. Keith gets caught in Shiro's wide, awed gaze as he stares up at him. Shiro doesn't know where to look, hands fluttering and eventually sliding down to settle on Keith's waist, solid and steadying as he breathes deeply and shifts experimentally on Shiro's cock.

“ _Keith_ ,” Shiro gasps, squeezing his eyes shut, and the sight is almost too much to bear, Shiro losing it because of _him_.

“Okay?” Keith asks, shocked by his own breathless voice, and Shiro nods, looking as overwhelmed as Keith feels.

Keith bites his lip and starts moving, keenly aware of his lack of experience – but it's okay, he thinks, flushing with embarrassment as he tries to stay balanced and ends up with his hands on Shiro's chest, because Shiro is new to this too, staring at Keith in awe and rubbing Keith's hips with his thumbs in a way he probably thinks is soothing but is actually sending shivers all the way up Keith's spine.

Eventually he works up a rhythm, rolling his hips and flexing his thighs, moans torn from his mouth every time he drops down because he's so _full_ , and Shiro's biting his lip hard, eyes so dark Keith can't see the grey anymore.

Keith's fingers dig into Shiro's chest and Shiro groans, and suddenly his hands are tightening on Keith's hips, _moving_ him and Keith whimpers, head falling forward as Shiro takes control, bouncing Keith on his cock and drawing cries from both of them.

Shiro's lips are parted like he wants to say something, but they're both panting too hard to form words. Keith straightens his back, gasping as Shiro slides deeper, and then he touches the place inside Keith that makes him cry out wildly, throat aching with it.

“Keith,” Shiro gasps, and his fingers dig sharply into Keith's hips to still him.

“Takashi,” Keith whimpers, squeezing his eyes shut against the stars spotting his vision, and Shiro grips him tighter.

“You okay?” Shiro asks, voice full of concern. Keith opens his eyes, takes in Shiro's flushed face and the way he's biting his lip, and a wave of desire comes over him so strongly he arches his back. “Keith?”

Keith, panting open-mouthed, manages a weak smile. “Yeah,” he hums, rocking his hips the little he can with Shiro holding him still, "You found my – “

“Oh,” Shiro says, abashed and wide-eyed, grip loosening enough for Keith to recreate their previous rhythm, thighs burning with the strain and eyes fixed on Shiro's, and Shiro starts thrusting up to meet Keith's movements, making Keith grab and claw at him for balance.

Shiro bites his lip in concentration, one hand heavy on Keith's hip and the other gripping Keith's ass and it's a heady feeling, Keith thinks hazily, Shiro moving him how he wants him, taking control.

Keith realises what Shiro is doing just as the next thrust has Shiro slide directly against his prostate, and his moan is raw and untamed, stars bursting all over his skin as Shiro adjusts and aims for that spot on every thrust, bouncing Keith harder and harder until he can't control his noises, fingers curling into Shiro's shoulders and eyes falling closed.

“Sh-Shiro,” he gasps, and Shiro's smirk is too much to bear, “ _oh_ , I'm – I'm so – “

“That's it,” Shiro whispers, eyes never leaving Keith's face. “You look so gorgeous like this, baby, come for me – “

Keith comes with a wail, squeezing his eyes shut and trembling with the force of it, coming all over Shiro's chest and meeting his gaze and his eyes are an inferno, burning into Keith's and making his exhales unsteady.

“ _Keith_ ,” Shiro breathes and Keith feels boneless, moaning weakly as Shiro thrusts twice more before coming, coming _inside_ him, and the thought makes Keith blush, even in the state they're in. Shiro makes a broken noise, and as shaking fingers release his hips Keith falls forward, catching himself just in time.

Shiro rolls them over and pulls out as carefully as he can. The sensitivity makes them both groan, but Shiro's whisper of, “Sorry,” makes Keith smile tremulously at him. Shiro remains hovering over Keith, a comforting weight pressing him down, and he curls his fingers around Shiro's neck and pulls him down for a kiss.

It's soft and sweet, worlds away from what they'd just shared, but neither of them have much energy for more than slow movements of their lips together, Keith's hand moving into Shiro's hair and Shiro cupping Keith's cheek.

When they break apart, Shiro hides his face in Keith's neck. “God,” he mutters, so quietly Keith barely hears. Keith runs his fingers through Shiro's hair, listening to their breathing sync. He makes a soft humming noise of agreement, and Shiro nestles closer to him.

Keith could almost fall asleep – it's almost perfect, lying with Shiro in his arms and feeling closer than ever – but he's uncomfortably aware of the soreness between his legs. When he shifts, he feels come trickle from his hole, and it brings a hot flush to his cheeks.

“I need to shower,” he murmurs, unwilling to ruin the moment.

“In a bit,” Shiro says, his voice just this side of pleading, and Keith acquiesces. He doesn’t want to get up, to face the world outside of himself and Shiro.

It’d be okay, he thinks, if they just lie here for a little while.

**Author's Note:**

> i hope this cheered some of you up after the day we've had
> 
> please leave a comment if you enjoyed, and you can find me on twitter at twitter.com/starboysheith and tumblr at starboykeith.tumblr.com !


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